A368432 Inverse permutation to A368431.

0, 1, 2, 3, 4, 5, 6, 7, 9, 10, 8, 11, 12, 13, 14, 15, 20, 21, 18, 22, 16, 17, 19, 23, 24, 25, 26, 27, 28, 29, 30, 31, 43, 44, 40, 45, 37, 38, 41, 46, 33, 34, 32, 35, 36, 39, 42, 47, 49, 50, 48, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 90, 91, 86, 92

Offset: 0

Author

Rémy Sigrist, Dec 24 2023

Keywords

• nonn
• look
• base

Examples

			A368431(42) = 46, so a(46) = 42.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..8191
• Rémy Sigrist, PARI program
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A368431.

Programs

PARI

See Links section.

Python

from itertools import islice
from functools import reduce
def uniq(r): return reduce(lambda u, e: u if e in u else u+[e], r, [])
def A368431gen():  # generator of A368431
    R, aset = [["0", "1"]], set()
    while R:
        r = R.pop(0)
        for b in r:
            d = int(b, 2)
            if d not in aset: yield d; aset.add(d)
        if len(r) > 1: R.append(uniq([r[k]+"0" for k in range(1, len(r))]))
        R.append(uniq([r[0]+"0", r[0]+"1"] + [r[k]+"1" for k in range(1, len(r))]))
def agen(): # generator of terms
    adict, n = dict(), 0
    for i, k in enumerate(A368431gen()):
        if k not in adict:
            adict[k] = i
        while n in adict: yield adict[n]; n += 1
print(list(islice(agen(), 70))) # Michael S. Branicky, Dec 24 2023